Lens apparatus and imaging apparatus having the same

ABSTRACT

A lens apparatus includes a first barrel configured to hold a first lens unit, a fixed barrel configured to hold a final lens unit, a focus lens unit driven by an actuator, and a positioning mechanism configured to determine positions of the first barrel and the fixed barrel in a rotational direction around an optical axis. The first barrel and the fixed barrel are directly connected, and the actuator and the focus lens unit are provided in a space formed by the first barrel and the fixed barrel.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a lens apparatus and an imagingapparatus having the same.

Description of the Related Art

Japanese Patent Laid-Open No. (“JP”) 2000-338380 discloses a lens barrelin which a main structural member excluding a rear barrel and a bayonetportion is integrally molded in order to improve the strength.

The lens barrel of JP 2000-338380 screws a mechanism for moving the lens(focus mechanism) onto a holding barrel (main structural member) aloneon the inner diameter side of the main structural member. In that case,the main structural member needs an end spread shape in which thediameter spreads from the attachment portion of the focus mechanism tothe front side. Thus, the diameter of the main structural member becomesunnecessarily large, and the weight of the lens barrel increases.

The lens barrel disclosed in JP 2000-338380 initially screws the focusmechanism onto the main structural member, and then joins lenses L1 toL4 with the respective lens pressers. When the focus mechanism is to bedisassembled due to a defect or dust or the like, the focus mechanismcannot be taken out until all the lenses L1 to L4 are disassembled andthus the disassembly performance is bad. It is inconvenient to fix thefocus mechanism deep in the lens barrel for the assembly. One solutionfor this problem is to widen the opening of the main structural memberon the front side, but the weight of the lens barrel increases.

SUMMARY OF THE INVENTION

The present invention provides a lens apparatus and an imaging apparatushaving the same, which can improve the strength and reduce the weight.

A lens apparatus according to one aspect of the present inventionincludes a first barrel configured to hold a first lens unit, a fixedbarrel configured to hold a final lens unit, a focus lens unit driven byan actuator, and a positioning mechanism configured to determinepositions of the first barrel and the fixed barrel in a rotationaldirection around an optical axis. The first barrel and the fixed barrelare directly connected, and the actuator and the focus lens unit areprovided in a space formed by the first barrel and the fixed barrel. Animaging apparatus having the lens apparatus also constitutes anotheraspect of the present invention.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a camera system according to an embodimentof the present invention.

FIG. 2 is a sectional view of a lens barrel.

FIG. 3 is an exploded view of the lens barrel.

DESCRIPTION OF THE EMBODIMENTS

Referring now to the accompanying drawings, a description will be givenof embodiments according to the present invention. Correspondingelements will be designated by the same reference numerals, and aduplicate description thereof will be omitted.

Referring now to FIG. 1, a description will be given of a configurationof a camera system 1 according to one embodiment of the presentinvention. FIG. 1 is a block diagram of a camera system 1. The camerasystem (imaging apparatus) 1 includes a lens barrel (lens apparatus) 101and a camera body 201. The lens barrel 101 is fixed to the camera body201 via a mount 414.

The lens barrel 101 includes a first lens (first lens unit) 401 a, adiaphragm unit 405, a second lens (second lens unit, focus lens unit)404 a, a third lens (third lens unit) 410 a, a fourth lens (fourth lensunit) 411 a, and a fifth lens (fifth lens unit, final lens unit) 412 a.Each lens is held by a barrel described later. The lens barrel 101further includes a gyro sensor 106, a lens-side main CPU 107, an imagestabilization drive source 108, a diaphragm drive source 109, and afocus lens drive source 110.

The lens-side main CPU 107 controls driving and calculates for theentire lens barrel 101. The lens-side main CPU 107 sends an instructionto the diaphragm drive source 109 to drive the second lens 404 a. Thelens-side main CPU 107 sends an instruction to the focus lens drivesource 110 and drives the diaphragm unit 405.

In the image stabilization control, the lens-side main CPU 107calculates a blur correction amount using a detection value of the gyrosensor 106 that detects a vibration, and sends an instruction to theimage stabilization drive source 108. The image stabilization drivesource 108 drives the fourth lens 411 a in the y direction (yawdirection) and the p direction (pitch direction) orthogonal to theoptical axis x based on an instruction from the lens main CPU 107,thereby providing an image stabilization.

The lens-side main CPU 107 further includes a determination unit thatdetermines the holding state of the lens barrel 101 or the camera body201 based on the detection value of the gyro sensor 106.

The camera body 201 includes an image sensor 202, a camera-side main CPU203, a release button 204, a main power supply 205, and an imagerecording medium 206. The image sensor 202 photoelectrically converts anobject image formed by the lens barrel 101 and outputs an electricsignal. The release button 204 is an operation member having a two-stagepressing configuration: The first stage will be called SW1 and thesecond stage will be called SW2. The SW1 provides an instruction for theimaging start preparation, such as a return from the imaging standby, astart of the image stabilization, a start of the autofocus, and a startof the photometry. The SW2 provides an instruction for capturing animage and recording the image in the image recording medium 206. Thecamera-side main CPU 203 supplies the power to the lens barrel 101 andexchanges the information with the lens-side main CPU 107 via a contactblock 415, which will be described later, provided on the mount 414.

FIG. 2 is a sectional view of the lens barrel 101. In FIG. 2, the upperhalf of the central axis shows a second barrel (focus lens unit) 404described later forms an image on the infinity side (image side). Thelower half shows the second barrel 404 forms an image on the closestside (object side). FIG. 3 is an exploded view of the lens barrel 101for each unit. In this embodiment, the lens barrel 101 is a long focuslens barrel.

The first barrel 401 holds the first lens 401 a. The first lens 401 aincludes a 1 a-th lens 445, a 1 b-th lens 446, and a 1 c-th lens 447. Inother words, the lens held by the first barrel 401 corresponds to thefirst lens 401 a. The first barrel 401 holds the lens provided closestto the object among the plurality of lenses provided in the lens barrel101.

The 1 a-th lens 445 and the 1 b-th lens 446 are held by a press ring.The 1 c-th lens 447 is held by another barrel, and is fixed onto thefirst barrel 401 by rollers. The first barrel 401 may be made of resinor metal, but the first barrel 401 in this embodiment is a metal barrelmade of metal to maintain a high strength sufficient to hold the heavyfirst lens 401 a. A first unit 442 includes the first barrel 401 and thefirst lens 401 a.

The guiding barrel (holding barrel) 402 has a guide groove 402 a. Thecam ring 403 has a cam groove 403 a and is rotatably held by the guidingbarrel 402 at a fixed position. The second barrel (focus barrel) 404holds the second lens 404 a by heat caulking. The lens held by thesecond barrel 404 corresponds to the second lens 404 a. The diaphragmunit 405 is fixed and held by the guiding barrel 402, and adjusts alight amount. The drive unit (actuator) 406 is fixed onto the guidingbarrel 402 and performs rotational driving by the power control. Thedrive unit 406 includes an annular type piezoelectric actuator. Therotational driving force of the drive unit 406 is transmitted to the camring 403, and the cam ring 403 rotates around the optical axis. Thesecond barrel 404 is engaged with the cam groove 403 a and is linearlyguided by the guide groove 402 a, so that it can linearly move along theoptical axis. The third barrel 410 holds the third lens 410 a and isscrewed and fixed onto the image-side end of the guiding barrel 402. Thelens held by the third barrel 410 corresponds to the third lens 410 a.

As described above, the cam ring 403, the second barrel 404, thediaphragm unit 405, the drive unit 406, and the third barrel 410 arefixed onto the guiding barrel 402. A guiding barrel unit 443 includesthese components. In this embodiment, the diaphragm unit 405 is fixedonto the guiding barrel 402, but may be fixed into the first unit 442.In this embodiment, the drive unit 406 includes an annular piezoelectricactuator, but the present invention is not limited to this embodiment.The drive unit 406 may include a linear actuator.

The fixed barrel 409 is a metal barrel made of metal. The fourth unit(image stabilization unit) 411 holds the fourth lens 411 a and is heldinside the fixed barrel 409 by rollers. The lens held by the fourth unit411 corresponds to the fourth lens 411 a. The fifth lens barrel 412holds the fifth lens 412 a that is a final lens unit, and is fixed ontoa fifth flame portion 409 b of the fixed barrel 409. The lens held bythe fifth lens barrel 412 corresponds to the fifth lens 412 a. The fixedbarrel 409 holds a fourth lens 411 a and the fifth lens 412 a which isthe final lens unit. In other words, the fixed barrel 409 holds thefinal lens provided closest to the image among the plurality of lensesprovided in the lens barrel 101.

As described above, the fourth unit 411 and the fifth barrel 412 arefixed onto the fixed barrel 409. The fixed barrel unit 444 includesthese components. The fixed barrel 409 may be a lens barrel made ofresin.

Next follows a description of a connection method of each unit in theassembly order. A description will now be given of a method ofconnecting the first unit 442 and the guiding barrel unit 443. Apositioning pin 401 b is attached to the first barrel 401. An engagementsurface 401 d is provided on the inner circumference of the first barrel401. The guiding barrel 402 has a positioning hole 402 b. An engagementsurface 402 d is provided on the outer circumference of the guidingbarrel 402. When the engagement surface 401 d is engaged with theengagement surface 402 d, the positions of the first unit 442 and theguiding barrel unit 443 in the direction (eccentric direction)orthogonal to the optical axis are determined. When the positioning pin401 b is engaged with the positioning hole 402 b, the positions of thefirst unit 442 and the guiding barrel unit 443 in the rotationaldirection around the optical axis are determined. When the screw 448 isfastened in a screw hole 401 g provided in the first barrel 401 whilethe first unit 442 and the guiding barrel unit 443 are connected to eachother, the first unit 442 and the guiding barrel unit 443 are connectedto each other.

Next follows a description of a method of connecting the first unit 442and the guiding barrel unit 443 in the connected state with the fixedbarrel unit 444. A positioning pin 401 c is attached to the first barrel401. An engagement surface 401 e is provided on the outer circumferenceof the first barrel 401. A positioning hole 409 c is provided in thefixed barrel 409. An engagement surface 409 e is provided on the innercircumference of the fixed barrel 409. When the engagement surface 401 eis engaged with the engagement surface 409 e, the positions of the firstunit 442 and the fixed barrel unit 444 are determined in the directionorthogonal to the optical axis. When the positioning pin 401 c isengaged with the positioning hole 409 c, the positions of the first unit442 and the fixed barrel unit 444 are determined in the rotationaldirection around the optical axis. In other words, the positioning pin401 e and the positioning hole 409 c serve as a positioning mechanismthat determines the positions of the first unit 442 and the fixed barrelunit 444 in the rotational direction around the optical axis. The firstunit 442 and the fixed barrel unit 444 are connected to each other byengaging the screw 449 with the screw hole 401 h provided in the firstbarrel 401 while the first unit 442 and the fixed barrel unit 444 areengaged with each other. Thus, the lens barrel 101 holding the opticalsystem is completed.

A description will now be given of a component configuration on theappearance side. A rubber ring 421 is adhered to the tip of a protectring 422 and screwed with the first barrel 401. A front exterior ring423 is screwed with the first barrel 401. A cover rubber 425 covers anunillustrated function button 424 fixed onto a front exterior ring 423.An operation ring 426 is a functional switch. A press ring 427 isscrewed into the first barrel 401 in the optical axis direction, androtatably holds the operation ring 426. An electronic focus ring 428 isengaged with the circumferential groove provided in the press ring 427by rollers and rotatably held by the press ring 427. A rotationdetection sensor 441 detects a rotational amount of the electronic focusring 428. The drive unit 406 is driven according to the rotationalamount detected by the rotation detection sensor 441. Thereby, thesecond barrel 404 moves forward and backward along the optical axis formanual focusing.

A rear exterior ring 429 is screwed into the fixed barrel 409 on theimage side of the fixed barrel 409 so as to cover the outercircumference of the fixed barrel 409. A filter holding frame 418 isfixed onto the rear exterior ring 429 and detachably holds an insertionfilter unit 413. The mount 414 is fixed onto the rear end of the rearexterior ring 429 and fixes the contact block 415 for an electricalconnection with the camera body 201. The contact block 415 is connectedto a control substrate 408 through a lead wire 416. A light shieldingbarrel 417 is fixed onto the mount 414. A tripod ring 431 is rotatablyheld on the outer circumference of the rear exterior ring 429 and fixesthe tripod seat 430. A distance scale window 433 is fixed onto the rearexterior ring 429, and used when the distance scale displayed on adistance scale ring 432 held by the drive unit 406 is confirmed from theoutside. An bearing 434 is fixed onto the rear exterior ring 429 androtatably holds the tripod ring 431. A click bearing 436 and a clickspring 437 are disposed on the tripod ring 431 and generate a clickfeeling at a 90° pitch when the tripod ring 431 is rotated.

Next follows an effect of the present invention according to the aboveconfiguration. This embodiment uses the electronic focus ring 428 formanual focusing. Thus, the manual focusing can be performed withoutmechanically connecting the cam ring 403 and the electronic focus ring428 to each other.

The conventional configuration that mechanically connects the cam ring403 and the electronic focus ring 428 to each other requires thestructure to pass inside the drive unit 406. More specifically, in orderto connect the first barrel 401 and the fixed barrel 409, the connectionbetween the fixed barrel 409 and the intermediate barrel, the connectionbetween the intermediate barrel and the guiding barrel 402, and theconnection between the guiding barrel 402 and the first barrel 401 arenecessary. In other words, the structure includes four parts of thefixed barrel 409, the intermediate barrel, the guiding barrel 402, andthe first barrel 401. If there are many parts between the front lens andthe fifth lens 412 a in fixing them, the accuracies of the partsthemselves and assembling variations and deviations deteriorate, and theeccentricity and tilt between the front lens and the fifth lens 412 adeteriorate. As a result, the optical performance deteriorates. Inaddition, the strength of the connecting portion of the structure needsto be sufficiently strong so that the connection can be maintained inresponse to an external force such as an impact. If there are manyconnecting portions, the strength guarantee is necessary at eachconnecting portion, and the reinforce clue is necessary by increasingthe thickness. As a result, this scheme may increase the size and weightof the lens barrel 101. When the drive unit 406 is held on the outercircumference side of the guiding barrel 402, the diameter of theguiding barrel 402 is smaller than the diameter of each of the fixedbarrel 409 and the first barrel 401. When the structure is connected ata portion with a small diameter, it is necessary to guarantee theconnection by an engagement of a small diameter. Thus, it is necessaryto increase the fastening force and to enhance the strength of thefastening portion in comparison with a case where the structure isreceived at a larger diameter. As a result, the weight of the lensbarrel 101 may increase.

This embodiment does not need to mechanically connect the cam ring 403and the electronic focus ring 428 to each other by using the electronicring system as a manual focus method. Therefore, the first barrel 401and the fixed barrel 409 can be directly connected to each other bycompletely enclosing the guiding barrel 402 and the drive unit 406inside the fixed barrel 409. Thereby, three parts of the first barrel401, the guiding barrel 402, and the fixed barrel 409 are locatedbetween the front lens and the fifth lens 412 a in fixing them. Thesmaller number of components suppresses the accuracy deteriorations ofthe components themselves, the assembly variations and deviation, andthereby the deterioration of the eccentricity and tilt between the frontlens and the fifth lens 412 a. As a result, the good optical performancecan be maintained. In addition, since the number of connecting portionsof the structure is as small as one and the connection is provided atthe outer circumference portion with a large diameter, it becomes easyto maintain the strength of the connecting portion, and the size andweight are smaller than those of the prior art configuration.

Thereby, the guiding barrel 402 and drive unit 406 can be provided in aspace formed by the first barrel 401 and the fixed barrel 409, and thefirst barrel 401 and the fixed barrel 409 can be directly connecteddirectly connected.

The connecting portion between the first barrel 401 and the fixed barrel409 (position of the surface on which the screw hole 401 h is provided)is provided on the object side of the position of the second lens 404 aclosest to the image side in the optical axis direction. In thisembodiment, the connecting portion is closer to the object side than theposition of the second lens 404 a closest to the object side in theoptical axis direction. When the connecting portion is closer to theimage side of the position of the second lens 404 a closest to the imageside, the originally large first barrel 401 becomes larger, which makesmanufacturing difficult and increases the cost. Since the first barrel401 holds a heavy front lens at its tip, the moment applied to theconnecting portion increases and it is necessary to increase thefastening force and strength of the fastening portion. Since thisembodiment provides the connecting position on the object side of theposition of the second barrel 404 closest to the image side, there is noneed to increase the strength of the fastening portion unnecessarily,which can reduce the weight and cost. Since the lens barrel 101 isdivided into the first unit 442, the guiding barrel unit 443, and thefixed barrel unit 444 at the optimum positions, each unit can be easilyfastened and the assembly becomes easy.

In this embodiment, the first barrel 401 and the fixed barrel 409 areconnected to each other after the position in the rotational directionaround each optical axis is determined by the positioning pin.Similarly, the first barrel 401 and the guiding barrel 402 are alsoconnected to each other after the position in the rotational directionaround each optical axis is determined by the positioning pins. Thereby,the first unit 442, the guiding barrel unit 443, and the fixed barrelunit 444 are connected to one another after their positions aredetermined in the rotational direction around their respective opticalaxes. Therefore, as compared with a case where the respective units arescrewed together, interference can be smoothly avoided when the positionin the rotational direction around the optical axis deviates and aclearance for avoiding the interference becomes unnecessary. A smallerdesign is available by reducing the clearance among the components.

This embodiment directly fixes the guiding barrel unit 443 onto thefirst unit 442 rather than the fixed barrel unit 444. Thereby, the tiltand decentering can be improved between the first lens 401 a and thesecond lens 404 a, and the optical performance of this optical systemcan be maintained.

Moreover, this embodiment directly fixes the third barrel 410 onto theguiding barrel 402 rather than the fixed barrel 409. Thereby, therelative tilt and decentering can be improved between the third lens 410a and the second lens 404 a, and the optical performance of this opticalsystem can be maintained.

A main engagement surface 401 f and a sub engagement surface 409 f areprovided on the outer circumference side of the connecting portionbetween the first barrel 401 and the fixed barrel 409. The diameter ofthe sub engagement surface 409 f is slightly smaller than the diameterof the main engagement surface 401 f. More specifically, the diameter ofthe sub engagement surface 409 f is smaller than the diameter of themain engagement surface 401 f by 0.1 mm. An engagement surface 429 f isprovided on the inner circumference surface of the rear exterior ring429 provided on outside of the main engagement surface 401 f and the subengagement surface 409 f. The radial distance between the mainengagement surface 401 f and the engagement surface 429 f is smallerthan the radial distance between the sub engagement surface 409 f andthe engagement surface 429 f. With such a configuration, the engagementsurface 429 f and the main engagement surface 401 f are engaged witheach other, and the sub engagement surface 409 f is slightly released.When an impact is applied to the lens from the outside, the engagementsurface 429 f supports the first barrel 401 with the main engagementsurface 401 f. This configuration can suppress a relative shift betweenthe first barrel 401 and the fixed barrel 409 in the directionorthogonal to the optical axis.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2018-148655, filed on Aug. 7, 2018, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A lens apparatus comprising: a first barrelconfigured to hold a first lens unit; a fixed barrel configured to holda final lens unit; a focus lens unit driven by an actuator; apositioning mechanism configured to determine positions of the firstbarrel and the fixed barrel in a rotational direction around an opticalaxis; and a holding barrel configured to hold the actuator and the focuslens unit, wherein the first barrel and the fixed barrel are directlyconnected, wherein the actuator and the focus lens unit are provided ina space formed by the first barrel and the fixed barrel, and wherein theholding barrel is connected to the first barrel and the holding barrelholds a lens unit located on an image side of the focus lens unit. 2.The lens apparatus according to claim 1, wherein the first barrel andthe fixed barrel are fixed by a screw.
 3. The lens apparatus accordingto claim 1, wherein a position where the first barrel and the fixedbarrel are connected to each other is located on an object side of aposition of the focus lens unit closest to an image side in the opticalaxis direction.
 4. The lens apparatus according to claim 1, wherein aposition where the first barrel and the fixed barrel are connected toeach other is located on an object side of a position of the focus lensunit closest to an object side in the optical axis direction.
 5. Thelens apparatus according to claim 1, wherein the holding barrel is aguiding barrel configured to linearly guide the focus lens unit, and tohold an annular piezoelectric actuator and a cam ring rotated by theannular piezoelectric actuator.
 6. The lens apparatus according to claim1, wherein the first barrel is a metal barrel.
 7. The lens apparatusaccording to claim 1, wherein the fixed barrel is a metal barrel.
 8. Thelens apparatus according to claim 1, further comprising: an exteriorbarrel fixed to the fixed barrel so as to cover an outer circumferenceof the fixed barrel, wherein the exterior barrel is engaged with thefirst barrel at an outer circumference of a connecting portion betweenthe first barrel and the fixed barrel.
 9. The lens apparatus accordingto claim 8, wherein a radial distance between the first barrel and theexterior barrel is smaller than a radial distance between the fixedbarrel and the exterior barrel.
 10. The lens apparatus according toclaim 1, further comprising a filter unit provided on an image side ofthe final lens unit.
 11. The lens apparatus according to claim 1,wherein the first lens unit is fixed in an optical axis direction. 12.An imaging apparatus comprising: a lens apparatus; and an image sensorconfigured to photoelectrically convert an object image formed by thelens apparatus and to output an electric signal, wherein the lensapparatus includes: a first barrel configured to hold a first lens unit;a fixed barrel configured to hold a final lens unit; a focus lens unitdriven by an actuator; a positioning mechanism configured to determinepositions of the first barrel and the fixed barrel in a rotationaldirection around an optical axis; and a holding barrel configured tohold the actuator and the focus lens unit, wherein the first barrel andthe fixed barrel are directly connected, wherein the actuator and thefocus lens unit are provided in a space formed by the first barrel andthe fixed barrel, and wherein the holding barrel is connected to thefirst barrel and the holding barrel holds a lens unit located on animage side of the focus lens unit.
 13. A lens apparatus comprising: afirst barrel configured to hold a first lens unit; a fixed barrelconfigured to hold a final lens unit; a focus lens unit driven by anactuator; a positioning mechanism configured to determine positions ofthe first barrel and the fixed barrel in a rotational direction aroundan optical axis; and a holding barrel configured to hold the actuatorand the focus lens unit, wherein the first barrel and the fixed barrelare directly connected, wherein the actuator and the focus lens unit areprovided in a space formed by the first barrel and the fixed barrel,wherein the holding barrel is connected to the first barrel, and whereinthe holding barrel is a guiding barrel configured to linearly guide thefocus lens unit, and to hold an annular piezoelectric actuator and a camring rotated by the annular piezoelectric actuator.
 14. An imagingapparatus comprising: a lens apparatus; and an image sensor configuredto photoelectrically convert an object image formed by the lensapparatus and to output an electric signal, wherein the lens apparatusincludes: a first barrel configured to hold a first lens unit; a fixedbarrel configured to hold a final lens unit; a focus lens unit driven byan actuator; a positioning mechanism configured to determine positionsof the first barrel and the fixed barrel in a rotational directionaround an optical axis; and a holding barrel configured to hold theactuator and the focus lens unit, wherein the first barrel and the fixedbarrel are directly connected, wherein the actuator and the focus lensunit are provided in a space formed by the first barrel and the fixedbarrel, wherein the holding barrel is connected to the first barrel, andwherein the holding barrel is a guiding barrel configured to linearlyguide the focus lens unit, and to hold an annular piezoelectric actuatorand a cam ring rotated by the annular piezoelectric actuator.